The brainwaves were assessed using an electroencephalography (EEG) machine.
Neuroscientists discover that two-way “conversations” with people in a permanent vegetative state will be possible thanks to an inexpensive device that can read their brain activity.
Researchers have discovered that some people in the state are able to understand what is being said to them and follow commands to think certain thoughts.
British researchers have been at the forefront of the project, which experts hope will “fundamentally change” the way such patients are cared for.
In the experiment, 16 patients at Addenbrooke’s Hospital in Cambridge and the University Hospital of Liege in Belgium were asked to imagine movements of their right hand and toes.
Their brainwaves were assessed using an electroencephalography (EEG) machine, which measures neuron activity using a skullcap wired with electrodes. In addition, 12 healthy volunteers were asked to perform the same task.
The scientists consequently deduced that three of the 16 could “repeatedly and reliably” imagine the movements, “despite being behaviourally entirely unresponsive”.
The principle focus of the study, published online in The Lancet, was to see if EEG was as good as MRI scanning at detecting such brain activity in these patients, because it is much cheaper and more portable.
The researchers found it was – but they were able to go much further than that.
Professor Adrian Owen of the Medical Research Council Cognition and Brain Sciences Unit in Cambridge worked on the project with seven others from Britain, Belgium and Canada.
They concluded: “Our findings show that this EEG method can identify covert awareness in patients diagnosed in the vegetative state with a similar degree of accuracy to other methods of detection; it is a considerably cheaper and more portable bedside technique.
“This method could reach all vegetative patients and fundamentally change their bedside assessment.”
They added that it could open up “routine two-way communication” with some patients.
“The degrees of freedom provided by EEG could take this technique beyond binary (two) responses to allow methods of communication that are far more functionally expressive, based on many forms of mental state classification,” they argued.
“The development of techniques for the real-time classification of these forms of mental imagery will enable routine two-way communication with some of these patients, allowing them to share information about their inner worlds, experiences and needs.”
Professor Susan Gathercole, director of the Medical Research Council Cognition and Brain Sciences Unit, said the discovery brought them “one step closer” to “pinpointing levels of awareness that were not previously possible”.
But Paul Matthews, professor of neurosciences at Imperial College, London, cautioned that there was still a way to go before two-way communication was possible.
“Can they be taught to use EEG to communicate more generally, rather as eye blinks can be used by patients with ‘locked in syndrome’?” he asked.
People who are in a vegetative state are distinct from those with ‘locked-in syndrome’, who are fully conscious but cannot move. Those with locked-in syndrome can often communicate by blinking. In February, French researchers found almost three-quarters of 91 people with locked-in syndrome reported they were happy.
Julian Savulescu, director of the Oxford Centre for Neuroethics, said the study “raises more ethical questions than it answers”.
“Are these patients suffering?” he asked. “How bad is their life? Do they want to continue in that state? If they could express a desire, should it be respected?”
He said: “For some of these patients, consciousness could be the experience of a living hell.”
And he advised: “We need guidelines for when life-prolonging treatment should be withdrawn in these minimally conscious states.”